tamron 28-75 vs canon 28-70 3.5

tamron and canon sharpness, tested with canon 5d mark 1, iso 400, tripod, and timer on camera

at 28mm wide open 2.8 vs 3.5 test corner canon, center even
28mm, 5.6 corner tamron, center tamron
28mm, f9 center tamron, corner slightly tamron

at 50 mm 2.8 tamron vs f4 canon, corner canon, center tamron
50 mm 5.6 corner canon, center even
50 mm f9 corner tamron, center tamron

at 70-75mm 2.8 vs 4.5 corner canon, center tamron slightly
70-75mm 5.6 corner canon, center tamron slightly
70-75mm f9, corner canon significant , center even but tamron has slight contrast edge

canon on left tamron on right at 5.6 70-75 mm both corners

center, had to crop tamron but its at 5.6 at 70-75, canon on left

also these crops were from one picture with the canon, and one picture with the tamron. The canon is a 35$ lens vs about a 250$ lens on ebay for the tamron. The canon is also only at 4.5 at 70mm and is sharp across the frame. To be fair the corner i included in the crop is the worst corner. But the canon was pretty equal in all corners. So on wide end tamron lets in about 175% more light, and about 235% more light on the long end.
Also, tamron colors were better. And when the tamron beat the canon it barely beat it, but when the canon beat the tamron, like in the long end, it smoked it.